U.S. patent application number 09/905496 was filed with the patent office on 2003-01-16 for system for exaust/crankcase gas recirculation.
Invention is credited to Hessel, Randy Paul, Mahakul, Budhadeb.
Application Number | 20030010328 09/905496 |
Document ID | / |
Family ID | 25420933 |
Filed Date | 2003-01-16 |
United States Patent
Application |
20030010328 |
Kind Code |
A1 |
Mahakul, Budhadeb ; et
al. |
January 16, 2003 |
System for exaust/crankcase gas recirculation
Abstract
An exhaust gas recirculation system for an internal combustion
engine by which a portion of exhaust gas from the engine is
recirculated from an exhaust line of the engine into an intake line
of the engine, introducing the exhaust gas flow into the intake
port around the intake valve seat region. The present invention
provides a unique means of introducing EGR/Crankcase gas into the
combustion chamber of an engine. The location for introducing
EGR/Crankacse gas is above the intake valve seat region. The system
does not require any pumping arrangement either through the use of
external pumps or by raising the exhaust back presssure in the
system. This system does not penalize airflow into the system as
the flow passage does not require reduction in size to the air
passage. Introducing the EGR just during the air induction process
means the quantity of exhaust gas in the system is minimal. This
results in improved transient response. Use of minimal EGR also
results in smaller EGR cooling system. The introduction of
crankcase into the combustion chamber results in lowering of the
particulates in the exhuast. The oil particles in the crankcase gas
also improves intake valve life.
Inventors: |
Mahakul, Budhadeb;
(Naperville, IL) ; Hessel, Randy Paul; (Middleton,
WI) |
Correspondence
Address: |
BUDHADEB MAHAKUL
1509 CANYON RUN ROAD
NAPERVILLE
IL
60565
US
|
Family ID: |
25420933 |
Appl. No.: |
09/905496 |
Filed: |
July 16, 2001 |
Current U.S.
Class: |
123/568.17 ;
123/572 |
Current CPC
Class: |
Y02T 10/12 20130101;
F02M 25/06 20130101; Y02T 10/121 20130101; F02M 26/23 20160201;
F02B 25/06 20130101; F02M 26/20 20160201 |
Class at
Publication: |
123/568.17 ;
123/572 |
International
Class: |
F02M 025/07; F02B
025/06 |
Claims
We claim:
1. An exhaust gas recirculation system for an internal combustion
engine by which a portion of exhaust gases produced by the engine
is recirculated, said arrangement comprising : an air intake line
supplying air into the engine through intake valves, an exhaust gas
recirculation pipe extending into the said air intake duct, a
pressure differential means for drawing a secondary flow from said
recirculation line into a primary flow in the said intake line, and
the actuation of the intake valves and induction stroke of the
engine, said high pressure exhaust line discharge disposed in said
recirculation line.
2. An exhaust gas recirculation system according to claim 1,
wherein said pressure differential means comprises high velocity
air upstream of intake valve region, resulting from actuation of
intake valves and induction stroke of the engine.
3. A location for connection of EGR gas in the air intake duct
according to claim 2 at a region of low pressure in the intake duct
in the close vicinity of the exhaust valve seat, said low pressure
region permits EGR into the intake duct.
4. An exhaust gas recirculation system according to claim 1,
wherein the exhaust pressure is lower than the intake line
pressure, said exhaust is drawn into the intake line at the low
pressure region above the valve seat.
5. An exhaust gas recirculation system according to claim 2,
wherein said source of high pressure air is a compressor of an
exhaust gas powered turbocharger having at least one turbine, said
exhaust line being connected to said at least one turbine
downstream of said EGR line, and said EGR line being connected to
the intake line, downstream of the said compressor.
6. An exhaust gas recirculation system according to claim 1,
wherein said source of high pressure air is a compressor of an
engine driven supercharger and having at least one turbine, said
exhaust line being connected to said at least one turbine
downstream of said exhaust gas line and said exhaust gas
recirculation line being connected to the intake line downstream of
said compressor.
7. An exhaust gas recirculation system according to claim 1,
wherein the source of high pressure air is the air induction
arrangement of a naturally aspirated engine, having exhaust line,
said exhaust line being connected to said EGR line, and said EGR
line being connected to the intake line upstream of the intake
valves.
8. A crankcase blowby gas recirculation system for an internal
combustion engine by which the crankcase blowby gas from the engine
is recirculated from the blowby line of the engine into the intake
line of the engine, a pressure differential means for drawing a
secondary flow from said crankcase blowby line into a primary flow
in the said intake line, and the actuation of the intake valves and
induction stroke of the engine, said blowby line discharge disposed
in said recirculation line.
9. An exhaust gas recirculation system according to claim 1 wherein
said exhaust gas recirculation line extends into the air intake
line in close proximity of the valve stems above the seat region to
introduce exhaust gas into the intake duct, said exhaust gas
pressure is higher than said intake duct pressure at the EGR
discharge line.
Description
BACKGROUND
[0001] 1. Field of Invention
[0002] This invention relates to exhaust gas recirculation (EGR) or
crankcase blowby gas recirculation system into an internal
combustion engine. More specifically this invention relates to an
exhaust gas recirculation system or crankcase blowby system to
reduce NOx emission and Hydrocarbon/Particulate emission.
[0003] 2. Description of Prior Art
[0004] With continued tightening of the emission standards for
internal combustion engines, particularly NOx, not only has the
need to recirculate exhaust gases back into the engine become
important, but also has the need to improve EGR technology. The
crankcase ventilation gases emit significant amount of particulate
and hydrocarbon into the exhaust. Therefore, a means to develop a
system to recirculate crankcase gas back into the engine intake
system becomes important.
[0005] Significant efforts in research and development have been
undertaken to re-circulate exhaust gas into the engine. The reason
for introducing EGR (exhaust gas re-circulation) in internal
combustion engines, is to reduce NOx emission without incurring
fuel consumption penalty. The difficulty in introducing EGR in
internal combustion engines is that it requires a pumping
arrangement or a venturi arrangement. This adds complexity and
penalty in fuel consumption. In addition, filling up the air intake
system with EGR often leads to poor transient response performance
for an internal combustion engine. A similar problem exists for
crankcase breathing arrangements for internal combustion engines.
The crankcase gases may not be vented to the atmosphere per various
Emissions regulations. This leaves the crankcase gas to be vented
either to the exhaust stream or be introduced ahead of the
compressor inlet in a turbocharged engine arrangement. Venting
crankcase gas into the exhaust causes an increase in Particulate
matter and Hydrocarbon emission. Also introducing the crankcase
gases ahead of the turbocharger causes significant issues with
fouling of the compressor and aftercoolers. Introducing the
crankcase gas into the air intake system will result in combustion
of the crankcase gas in the cylinder. This results in lowering of
particulate and hydrocarbon emission.
[0006] In general, the exhaust gas pressures in the exhaust
manifold for an internal combustion engine are lower than the
pressures in the air intake manifold. This provides positive
breathing and increased pumping work which results in improved fuel
economy.
[0007] To deliver EGR to the air intake system, higher exhaust gas
pressure is needed, for a system without any pump. Often the
turbocharger is resized to obtain higher exhaust gas pressure. This
results in loss of fuel economy.
[0008] U.S. Pat. No. 5,611,203 to Henderson et al (1997) discloses
that creating a venturi in the Intake runner pipe will allow
exhaust gas to be drawn. This system will provide EGR supply at
higher when there is a sufficient flow of air to create a venturi.
However at part load the supply of EGR is limited. To overcome this
problem some designs have used a smaller bypass pipe in parallel
with valve arrangements. At light load the main air passage is
closed and air is diverted through the smaller pipe. This system
requires throttling of the Intake runners and complicated valve
arrangement for part load EGR delivery. Throttling of the Intake
air results in fuel consumption loss and potential for increase in
particulate.
[0009] Another U.S. Pat. No. 6,044,827 to Pfaffet al (2000)
describes a complex exhaust gas recirculation arrangent having
valves and ejector placed in the air inlet duct. The supply of
exhaust gas to the system will require higher exhaust pressure or a
pumping arrangement. Both these features will result in fuel
consumption loss and in a complicated system.
SUMMARY OF THE INVENTION
[0010] In view of the foregoing, it is a primary object of the
present invention to provide an exhaust gas recirculation (EGR) or
a crankcase ventilation system in which the opening of the intake
valves and the induction stroke will cause the exhaust gas or
crankcase gas to be introduced into the engine under all
conditions.
[0011] In keeping with the foregoing object, it is an associated
object of the present invention to enable EGR or crankcase
ventilation gas to be effectively utilized on an internal
combustion engine having or not having a supercharger or a
turbocharger.
[0012] It is a more specific object of the present invention to
achieve the above objects through the use of an improved
construction for a means of connecting exhaust gas/crankcase gas
into the engine intake system located in close proximity of the
intake valve seats.
[0013] Another specific object of the present invention to achieve
the above objects by providing a means for introducing low pressure
exhaust gas or crankcase ventilation gas into the engine intake
system.
[0014] These and other object are achieved by preferred embodiments
of the present invention.
[0015] The present invention defines a unique exhaust gas
recirculation(EGR)/Crankcase gas recirculation arrangement.
EGR/Crankcase gas is admitted into the engine with modifications in
the cylinder head air inlet ports. Air flows into the cylinder as
the intake valves open. The air induction stroke results in high
velocity of the Intake air around the valve seat region due to the
pressure gradient between the ports and the cylinder (FIG. 1). This
increase in velocity leads to a region of low pressure. Introducing
the exhaust gas from the exhaust manifold directly into the valve
seat region will cause the exhaust to be drawn into the cylinder
(FIG. 2). This arrangement may be utilized for drawing in crankcase
ventilation gas also. A simulation was performed with a
Computational fluid dynamics package to confirm this claim. The
results of the simulation show the pressure distribution around the
valve seat area of the inlet port (FIG. 1). It is clearly shown
that the pressure in the valve seat region is significantly lower
than the air supply pressure to the ports. For this case, the
simulation started just prior to intake valve opening. At that
crank angle, pressures and temperatures throughout the flow domain
were uniform. Pressures and temperatures at the port ends were also
equal. The figures show the pressure field at 80 degrees
after-top-dead-center. This crank angle was chosen because the
piston is moving fast then, resulting in large velocities in the
valve curtain region, which give the lower pressures seen in the
figure. At light load engine operation when the boost pressure is
significantly low, the air induction process in the cylinder will
draw in the exhaust gas into the cylinder. This system will ensure
that EGR is supplied into the engine cylinder under all operating
conditions. A pumping arrangement may be utilized to further
enahnce the quatities of EGR/crankcase gas into the air intake port
of an internal combustion engine. An actuator that will control the
amount of flow into the cylinder shall provide the control of the
exhaust into the cylinder. The actuator may be operated by a
mechanical/hydraulic/pneumatic/electric- al system. A simple design
is shown in FIG. 3, which comprises of a pipe from the exhaust that
is fed into a cooler. The amount of exhaust gas flow into the
cylinder is controlled by the actuator that feeds into the
individual cylinders. The exhaust gas flows into the cylinder only
when the intake valves are open. The ability to supply exhaust gas,
during the intake process, will result in minimal exhaust gas
present in the intake port. This significantly improves transient
response compared to other systems. Also due to the small
quantities of exhaust gas being circulated in the system, the
amount of exhaust gas cooling required will be minimal. The
arrangement for crankcase gas is shown in FIG. 4. The crankcase gas
is directly fed into the intake valve seat region as shown. The
ability to introduce the crankcase gas back into the cylinder will
result in significant reduction in particulate without causing any
deterioration to engine performance.
[0016] These and further objects, features and advantages of the
present invention will become apparent from the following
description when taken in connection with the accompanying drawings
which, for purposes of illustration only, show several embodiments
in accordance with the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 Simulation results from Computational fluid dynamics
showing velocity vectors and pressure distribution in the intake
manifold and cylinder.
[0018] FIG. 2 Simulation results from Computational fluid dynamics
showing exploded view of FIG. 1 in the intake valve region. Also
shown is the location of EGR/Crankcase gas inlet line.
[0019] FIG. 3A schematic depiction of an EGR system in accordance
with present invention.
[0020] FIG. 4A schematic drawing of a Crankcase ventilation system
in accordance with present invention.
[0021] FIG. 5A schematic drawing showing an arrangement of
EGR/Crankcase gas introduction line into the intake port in the
vicinity of the intake valve.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The present invention will be described hereinafter with
reference to the preferred embodiments thereof in conjunction with
the accompanying drawings. First referring to FIG. 3, indicated at
8 is an internal combustion engine; 9, an intake port and 5 and
exhaust manifold. The intake port 9 and exhaust manifold 5 are
connected to each other by means by means of a recirculation pipe
2, EGR cooler 4 and exhaust gas control valve 3. To introduce EGR
into the system, exhaust gas is drawn from the system before the
turbocharger 5 and led through the pipe 2 into an EGR cooler 4.
From there the exhaust gas is fed through the control valve 3,
which regulates the quantity of EGR into the intake port/s location
1.
[0023] The operation of the crankcase gas arrangement is shown in
FIG. 4. Blowby gas 2 from the crankcase is directed into the oil
separator 3. From there the crankcase gas is led to the intake port
location 1 above the valve seat area. This will ensure a positive
flow of crankcase into the engine. The ability to reintroduce the
crankcase gas into the system results in lower particulate emission
as the oil particles in the crankcase gas are burnt in the
cylinder. Also the oil mist in the gas enhances the life of the
intake valve seat.
[0024] FIG. 1 shows the simulation results from a turbocharged
engine outlining the velocity vectors and pressure distribution
around the intake valve seat region resulting from air induction
stroke and opening of the intake valve. This increase in velocity
leads to a region of low pressure around the valve seat region.
Introducing the exhaust gas from the exhaust manifold directly into
this valve seat region will cause the exhaust to be drawn into the
intake port. FIG. 2 shows an exploded view of the pressure
distribution along the valve seat region.
[0025] Further improvements in creating a low pressure region
around the valve seat has been shown in FIG. 5. Extending the EGR
line 1 in the air intake port 2 in close vicinity of the valve 3
increases the amount of exhaust gas that can be drawn into the
engine.
[0026] While various embodiments in accordance with the present
invention have been shown as described, it is understood that the
invention is not limited thereto, and is susceptible to numerous
changes and modifications as known to those skilled in the art.
Therefore, this invention is not limited to the details shown and
described herein, and includes all such and modifications as are
encompassed by the scope of the appended claims.
[0027] The present invention will find applicability for use on a
wide range of engine types for purposes of meeting stringent
emission regulations, particularly those applicable tubo-equipped
diesel engine.
* * * * *